The reflective optical sensor module emits light and measures the amount of reflected light from an object. The optical sensor module converts electrical current into light, which is directed onto the surface of an object, and converts the reflected light into electrical signals. The incident light can then be reflected by the object, absorbed by the object, or scattered by the object. A portion of reflected and scattered light can reach a photodetector of the optical sensor module; the received reflected and scattered light produces a corresponding signal. The acquired optical signals may be computed as useful information. For example, the blood oxygen saturation level is based on the light absorption rate of particular wavelengths. Further physiological information may be derived from the acquired optical information at multiple parts of human body. People confront a problem with obtaining information simultaneously from multiple parts of human body or reproducibly at the exact same sites. Previous solution is either to measure multiple regions sequentially, or to combine several sensor devices for multi-site measurement. However, simply applying a sensing device or several independent sensing devices on multiple sites introduces additional temporal or spatial errors (for example, from phase differences, or inter-experimental variation).